METHOD AN APPARATUS FOR MEASURING THE PH OF PURE WATER

摘要

The apparatus of the invention includes a flow chamber having an inlet, an outlet, and a removable cover. The cover includes fittings for mounting a reference electrode assembly, a measuring electrode assembly, and a combined counter electrode/thermistor probe. According to the one illustrative embodiment invention, the flow chamber is substantially cylindrical with the inlet located near the bottom of the chamber and the outlet located near the top of the chamber. The axes of the inlet and outlet lie in the same plane as and are parallel to a diameter of the chamber. The inner diameter of the inlet is reduced to approximately ⅛″ so that the velocity of water entering the chamber is increased. The inner diameter of the outlet is approximately ¼″ so that the velocity of water exiting the chamber is less than the velocity of water entering the chamber. The reference electrode is located with its porous frit directly above the inlet and the measuring electrode is located adjacent to the outlet. The inlet flow is dynamically balanced for optimum performance of the reference electrode. The molarity of KCl in the reference electrode and the flow rate of the reference frit are balanced with the inlet turbulence. The balance of these parameters significantly reduces or eliminates noise related to the effects of parasitic junction potentials thereby significantly increasing the accuracy of the measurements.